This invention relates to a ventilating system for the passenger compartment of an automotive vehicle. More particularly, this invention relates to such a ventilating system in which air is channeled to the vehicle's passenger compartment via an interspace between the vehicle roof and a roof lining.
The passenger compartment of an automobile generally has a size of 2 to 3 m.sup.3. In order to cool the passenger compartment in warm weather, 300 to 700 m.sup.3 /h of ambient air or air cooled by an air conditioning system are guided through the compartment. Such a high rate of air flow results in many air changes with heavy drafts on the passengers. Opening the side windows of an automobile or sliding roofs likewise leads to large changes in the air in the passenger compartment and at high speeds can result in harmfully high air velocities and noises in the passenger compartment. Because of the annoyance of drafts and of the fear of catching cold, sensitive people frequently dispense with an effective cooling of the passenger compartment.
If, in overheated vehicles, individual passengers direct air discharge nozzles in the dashboard at themselves, the outflowing air can fall on perspiring passengers and lead to rheumatic complaints or to colds.
In order to improve air distribution, cooled air can be conducted through the space between the vehicle roof and the roof lining and let out above the driver. This solution to the ventilating problem, as set forth in U.S. Pat. No. 2,720,149, has required a double-walled rear window which is disadvantageous in passenger vehicles because of the added weight. In addition, only a small improvement of air flow is obtained.
As described in German Patent No. 950 110, the forward roof struts can be used for conducting air from a heat exchanger into an interspace between the roof and a roof lining, the air flowing from the interspace laterally towards the side windows and back towards the rear window of the automobile. While air distribution is improved by such an arrangement, the relatively narrow flow channels are exposed to the sun and cause the air to be heated before it enters the roof space.
A ventilating system is known in which air flows between the roof of a vehicle and a continuous roof lining from the front towards the rear of the vehicle. The roof lining is spaced a predetermined constant distance from the vehicle roof and is provided with outlet openings. The space between the vehicle roof and the roof lining serves to conduct the air. The purpose of this known system is to maintain the window panes of the vehicle free of condensation and frost especially at the beginning of a journey and to ensure a clear view through the windshield and the rear window. Accordingly, air is conducted from the front of the vehicle to the rear without drafts to ensure rapid defrosting. Heated air is blown out of several slots extending parallel to the windshield, is conducted parallel to the windshield and is subsequently guided into the roof space by means of sun visors which must be disposed in predetermined positions for this purpose. From the roof space, the air is conducted essentially along the roof to the rear window. A disadvantage of this arrangement is that the air stream flowing along the windshield can be deflected if the sun visors are not properly positioned. The air can in some instances be deflected upon passengers sitting nearby. The guiding of the air therefore depends on the positioning of the sun visors and is not effective in the sun visors are moved to the side. Moreover, because of the multiplicity of slots parallel to the windshield and because of their small cross-sectional areas and correspondingly large jet surfaces, a large portion of the kinetic energy of the air stream is converted by injection before it reaches the upper edge of the windshield. The high pressure required in the region of the upper edge of the windshield necessitates a high exit velocity with a concomitantly high level of noise. In addition, the flow from the rood lining is non-uniform and practically no outflow occurs in the forward range with the high air velocities. Finally, the outflow is towards the rear end of the vehicle rather than perpendicularly into the passenger compartment.
In this known ventilating system, the lower part of the roof lining consists of the same material as the upper part and is provided along its entire extent with relatively small air exit openings. For maintaining a uniform distance between the upper part of the roof and the lower part thereof, a thin support wall having an accordion profile is provided, the support wall being drawn in between the mutually facing flat sides of the upper and lower parts of the roof lining. In that manner, an interspace is created which has an approximately uniform cross-section over its length and which is open towards the rear window of the vehicle. That arrangement, however, is unsuitable for distributing cooled air, for example, from an air conditioner to the passenger compartment free of drafts. The arrangement is further dependent on incident solar radiation inasmuch as the positioning of the sun visors may disturb or destroy their functioning as air guide elements.
An object of the present invention is to provide an improved ventilating system of the above-mentioned type.
Another object of the present invention is to provide such a ventilating system in which a substantially uniform low-velocity air flow is achieved.
Yet another object of the present invention is to provide such a ventilating system which has reduced noise.
Another, more particular, object of the present invention is to provide such a ventilating system which is independent of the positioning of the sun visors.
Yet another particular object of the present invention is to provide such a ventilating system in which air flow to individual passenger seats can be essentially independent of air flow towards other seats.